The present invention relates generally to a method and apparatus for adjusting an orthodontic appliance, and more particularly to a hand-held tool and an associated technique employed by the wearer or assistant to adjust the amount of pressure applied by an expansion device to the wearer's teeth and palate.
A palatal expander is a well-known device whose function is to gradually spread the maxillary arch and thereby provide greater space for proper alignment of the upper teeth. Typically, such an appliance is formed with a segmented body disposed in the palatal cavity, a pair of stainless steel wires extending laterally from opposite sides of the body, and a tooth-engaging band secured at the free end of each wire. The bands are secured, for instance, to the first molars and first bicuspids. The segmented body is provided with means for lateral expansion, typically an elongated shaft threadedly mounted in relatively opposing segments of the body. The shaft is formed with an enlargement or turning block having a plurality of radially extending and outwardly opening bores. By rotating the shaft in one direction the body expands laterally, thereby exerting pressure on the banded teeth of the user. This pressure is transferred to the palate and, after a relatively brief period of time, is dissipated by the gradual expansion of the connective tissue or sutures disposed between the palatine bones. Additional pressure must be applied twice a day by turning the shaft to further expand the appliance until the palatine arch has been extended to provide sufficient space for the proper alignment and positioning of the upper teeth. In view of the need for frequent adjustment of the expander, it is desirable for the device to be designed so that the wearer can adjust it. Accordingly, the conventional palatal expander is constructed in such a manner that the wearer can insert a wire or pin into one of the several bores found in the turning portion of the adjustment shaft and pivot the wire, thereby rotating the shaft and expanding the device. This process is repeated until the required pressure is achieved.
In the past, the adjustment tool, known as a wire key, comprised a relatively short, straight segment of wire rigidly extending from a gripping portion. To adjust the palatal expander, the patient would grasp the wire key, insert the hand and key into the mouth, insert the straight end portion of the key into the turning block portion of the stem and pivot the tool, thereby turning the stem and spreading the segments of the expander outwardly.
The old adjustment tool had several drawbacks. The tool was short, so it was difficult to view the instrument in the mirror, as the user's hand would typically block the view. Furthermore, since the entire tool was inserted in the user's mouth, there was a danger of it being swallowed or becoming lodged in the throat. Also, since the tool required the user to insert a finger or fingers into the mouth, there was a likelihood of activating the gag reflex.
The palatal expander of Siatkowski, as disclosed in U.S. Pat. No. 3,977,082, was equipped with an anteriorly or forwardly disposed adjustment stem which was turned by pivoting the wire key adjustment tool to the left or right. In this manner, the problems associated with inserting the wire key far into the mouth were lessened. However, in view of the proximity of the turning block on the Siatkowski expander to the front teeth of the user, it would be difficult to sight and manipulate the wire key into the adjustment stem.
Thus, the present inventor was faced with the problem of devising an adjustment tool and an associated technique that would be easier and safer for the wearer to employ in adjusting the palatal expander.